Martin McGuinness has announced his resignation as Deputy First Minister of Northern Ireland in protest at the Democratic Unionist Party’s handling of a botched renewable energy scheme.
The Sinn Fein veteran’s move, which will come into effect at 5pm on Monday, is likely to lead to a snap Assembly election in the region.
Mr McGuinness announced his decision after his partner in government, DUP First Minister Arlene Foster, repeatedly refused to step down to facilitate a probe into the ill-fated Renewable Heat Incentive (RHI) - a scheme that has left Stormont facing a £490 million overspend.
Mr McGuinness said he was resigning with “deep regret and reluctance”.
“The First Minister has refused to stand aside, without prejudice, pending a preliminary report from an investigation.
“That position is not credible or tenable.”
He made clear that Sinn Fein would not replace him in the role.
As a consequence, the collapse of the institutions and an election are now inevitable.
“We now need an election to allow the people to make their own judgment on these issues democratically, at the ballot box,” he said.
Mrs Foster presided over the ill-fated RHI while economy minister.
She has steadfastly refused to accede to Sinn Fein’s demand for her to step aside to facilitate an inquiry into her actions.
The fate of the current DUP/Sinn Fein administration in Belfast now hangs on the pivotal issue of whether or not she will stand down.
The state-funded RHI was supposed to offer a proportion of the cost businesses had to pay to run eco-friendly boilers, but the subsidy tariffs were set too high and, without a cap, it ended up paying out significantly more than the price of fuel.
This enabled applicants to “burn to earn” - getting free heat and making a profit as they did so.
Claims of widespread abuse include a farmer allegedly set to pocket around £1 million in the next two decades for heating an empty shed.
Mr McGuinness’s move comes hours after Mrs Foster accused him of playing a political game of chicken and warned she would not blink first.
“If he is playing a game of chicken, if Sinn Fein are playing a game of chicken, and they think we are going to blink in relation to me stepping aside they are wrong - I won’t be stepping aside,” she said.
“And if there is an election, there is an election.”
While Sinn Fein had been due to formally call for Mrs Foster to step down in an Assembly debate next week, there had been speculation the party would pull the plug earlier.
Mr McGuinness, who has been experiencing health problems, confirmed that on Monday afternoon.
“It is my firm view that the DUP’s handling of this issue has been completely out of step with a public mood which is rightly outraged at the squandering of public money and the allegations of misconduct and corruption,” he wrote in his resignation letter to the Assembly’s speaker.
“The public are demanding robust action and accountability but the DUP, in particular its leader Arlene Foster, have refused to accept this.”
The structure of Stormont’s Executive Office means a First Minister cannot hold the position without a co-equal Deputy First Minister. Mr McGuinness’s resignation means Mrs Foster will no longer be First Minister.